Ckpool is open-source software as per the thread linked above if you go read it.
Also to note : the public github is not maintained anymore for CKPool as he does development privately only now. Also with the CKPool code the code does not include a payout coding to handle the payouts so you will need to develop that. I suggest if you not a great programmer don't bother with that software as it will not be maintained.
Take a look at MPOS code and if you keep your pool private it will work as a solo pool
Edit: Please note it's suppose to be CKDB where I have said CKPool.